In recent years, portable information processing apparatuses (hereinafter also referred to as electronic equipment) which can be carried by users are becoming popular. For example, the portable information processing apparatuses include Personal Computers (PCs), cellular phones, smartphones, notebook PCs, tablet PCs, Personal Digital Assistants (PDAs), digital cameras, and game machines. The portable information processing apparatuses tend to be made smaller and thinner.
The smaller and thinner information processing apparatuses can charge a battery built in the information processing apparatuses and add an external interface by connecting auxiliary apparatuses, such as cradles and docking stations. Connection between the information processing apparatuses and the auxiliary apparatuses such as cradles is established by connecting, for example, a cradle connector provided in the information processing apparatuses to a main-body connector provided in the auxiliary apparatuses such as cradles. In the smaller and thinner information processing apparatuses, the same connector is used for battery charge and for access to external interface as it is desirable to reduce the number of components provided in their casings.
The auxiliary apparatuses such as cradles and docking stations provide such functions as power supply that charges the information processing apparatuses, through the respective connectors. The auxiliary apparatuses such as cradles also provide the information processing apparatuses with external interface functions, including interfaces to peripheral devices, such as external displays and keyboards, and to external networks, through the respective connectors.
A model of the aforementioned information processing apparatuses which further has a waterproof function is becoming popular. When the information processing apparatuses have the waterproof function, the apparatuses can be used under such a condition as rainy weather, within the range guaranteed by the waterproof function, for example. In the information processing apparatuses having the waterproof function, a waterproofed connector is used as a connector for the cradle connection, for example. Use of the waterproofed connector enables the information processing apparatuses to suppress infiltration of raindrops, water, or other fluids into the casings. The information processing apparatuses can suppress short-circuit failures of various devices inside the casings caused by infiltrated water or other fluids.    [Patent document 1] Japanese Laid-open Patent Publication No. 2004-342611    [Patent document 2] Japanese Laid-open Patent Publication No. 2004-227071    [Patent document 3] Japanese Laid-open Patent Publication No. 2007-257128